Certain proteins, like growth factors have significant potential to treat neurodegenerative disease. Accordingly, it should be possible to stimulate the growth of endogenous progenitor stem cells so that they could enhance the natural course of injury repair. Unfortunately, the blood brain barrier forms a significant hurdle that limits the clinical utility of most peptides. We propose to apply principles of medicinal biology and combinatorial pharmacology to improve the delivery of growth factors to the brain and describe a comprehensive strategy to address a major problem in the development of CNS biotherapeutics: drug delivery to the brain.